Helium recovery refers to the collection of helium from the process of use for reuse. There are various methods for helium recovery, purification, and liquefaction, among which the common ones are achieved through cooling and compression. When helium is cooled to a temperature below its boiling point, it will become a liquid. Therefore, by exposing helium to a low-temperature environment, it can be liquefied. Common cooling methods include using liquid nitrogen or a refrigerator.

在液化过程中，氦气被收集到一个密封的容器中。然后，通过将容器放置在低温环境中，氦气逐渐冷却并转化为液体。在这个过程中，需要注意控制温度和压力，以确保氦气能够顺利液化。一旦氦气液化，它可以被储存和运输，以供后续使用。

During the liquefaction process, helium is first collected into a sealed container. Then, by placing the container in a low-temperature environment, the helium gas gradually cools and converts into a liquid. During this process, attention needs to be paid to controlling temperature and pressure to ensure that helium can be liquefied smoothly. Once helium is liquefied, it can be stored and transported for subsequent use.

然而，液化只是氦气回收的步。为了提高氦气的纯度，还需要进行提纯过程。氦气的提纯通常涉及到去除杂质和其他气体。常见的提纯方法包括分子筛吸附、膜分离和凝固分离等。

However, liquefaction is only the first step in helium recovery. In order to improve the purity of helium, a purification process is also required. The purification of helium usually involves removing impurities and other gases. Common purification methods include molecular sieve adsorption, membrane separation, and coagulation separation.

分子筛吸附是一种常用的氦气提纯方法。它利用分子筛材料的特殊结构和吸附性能，将杂质和其他气体从氦气中吸附出来。通过调节吸附剂的选择和操作条件，可以实现对氦气的高效提纯。

Molecular sieve adsorption is a commonly used method for helium purification. It utilizes the special structure and adsorption performance of molecular sieve materials to adsorb impurities and other gases from helium. By adjusting the selection of adsorbents and operating conditions, efficient purification of helium can be achieved.

膜分离是另一种常见的氦气提纯方法。它利用特殊的膜材料，通过选择性透过和阻挡不同气体分子的特性，将杂质和其他气体从氦气中分离出来。膜分离具有操作简单、能耗低等优点，因此在氦气提纯中得到了广泛应用。

Membrane separation is another common method for helium purification. It utilizes special membrane materials to selectively penetrate and block different gas molecules, separating impurities and other gases from helium. Membrane separation has been widely used in helium purification due to its advantages of simple operation and low energy consumption.

凝固分离是一种基于物质的凝固点差异的提纯方法。通过控制温度和压力，使氦气中的杂质和其他气体凝固，然后将其分离出来。这种方法适用于氦气中含有高沸点杂质的情况。

Solidification separation is a purification method based on the differences in solidification points of substances. By controlling temperature and pressure, impurities and other gases in helium are solidified and then separated. This method is suitable for situations where helium contains high boiling point impurities.

总结起来，氦气回收和提纯的液化过程是通过冷却和压缩将氦气转化为液体，并通过分子筛吸附、膜分离和凝固分离等方法去除杂质和其他气体。这些过程需要精确的控制和操作，以确保氦气的高效回收和提纯。通过回收和提纯氦气，我们可以更好地利用有限的资源，并为各个领域的应用提供高质量的氦气。

In summary, the liquefaction process of helium recovery and purification involves converting helium into liquid through cooling and compression, and removing impurities and other gases through methods such as molecular sieve adsorption, membrane separation, and solidification separation. These processes require precise control and operation to ensure efficient recovery and purification of helium. By recycling and purifying helium, we can better utilize limited resources and provide high-quality helium for applications in various fields.